Apparatus for capturing axial force on an inner drive member

ABSTRACT

A spindle with a mechanism for transferring axial force from an inner drive assembly to an outer drive assembly. The spindle&#39;s inner drive shaft is connected to an inner member of a dual-rod pipe by a drive rod having a sliding sleeve. The sleeve is fixed rotationally with the drive shaft, but not axially. When axial force drives the drive rod toward the drive member of the spindle, the sleeve contacts a stop member which is paired to the outer drive assembly. The stop member may be a pair of dowel pins. Axial force is thereby transferred from the inner member to the outer member, allowing such forces to be absorbed by the outer member&#39;s larger drive components.

SUMMARY

The present invention is directed to an apparatus. The apparatuscomprises an inner member, an outer member, an inner drive shaft, ahollow sleeve, and at least one pin. The inner member is disposed alonga longitudinal axis. The outer member is at least partially surroundingthe inner member and disposed about the longitudinal axis. The innerdrive shaft is coupled to a motor. The hollow sleeve is joined to theinner member in sliding, torque-transmitting engagement with the innerdrive shaft. The at least one pin is disposed through the outer memberand transverse to the longitudinal axis. The at least one pin isconfigured to transmit axial force from the hollow sleeve to the outermember.

The present invention is also directed to a spindle. The spindlecomprises an inner drive rod apparatus, a hollow outer member, and atleast one stop member. The inner drive apparatus is disposed about alongitudinal axis and comprises a drive shaft, an inner drive rod, and ahollow sleeve. The inner drive rod is configured for connection to aninner member of a dual-member drive string. The hollow sleeve has afirst end, a second end, and an internal surface. The hollow sleeve isslidingly supported and rotationally coupled to the drive shaft at itsinternal surface and joined to the drive rod at its first end. Thehollow outer member is at least partially disposed about the inner driverod apparatus. The outer member is independently rotatable relative tothe inner drive rod apparatus. The at least one stop member is supportedby the outer member and configured to engage with the second end of thehollow member.

In another aspect the invention is directed to an assembly forconnecting a dual-member drill string to a gearbox. The dual-memberdrill string comprises independently rotatable inner and outer members.The assembly comprises an inner assembly, an outer assembly, and a stopmember. The inner assembly is connected at a first end to the gearboxand a second end to the rotatable inner member of the dual-member drillstring. The inner assembly comprises a drive shaft, a drive rod, and ahollow sleeve. The drive shaft is rotatable about a longitudinal axisand has a first outer diameter. The drive rod is configured for torquetransmitting connection to the rotatable inner member. The hollow sleevehas a second outer diameter and is joined to the drive rod and partiallysurrounding the drive shaft in a torque-transmitting relationship. Thehollow sleeve is configured to move axially relative to the drive shaft.

The outer assembly comprises a cavity in which the hollow sleeve anddrive shaft are partially housed. The cavity defines a first innerdiameter. The first inner diameter is greater than the first outerdiameter and the second outer diameter. The stop member is disposedthrough the outer assembly and extends into the cavity. An effectiveinner diameter of the cavity at the stop member is greater than thefirst outer diameter and less than the second outer diameter.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is dual pipe drill gearbox for use with a horizontal directionaldrilling machine.

FIG. 2 is a top view cross section of the gearbox of FIG. 1.

FIG. 3 is a perspective view of the spindle assembly as shown in FIG. 1.The gearbox shown in FIGS. 1-2 is attached to the right of the figure.

FIG. 4 is a cross section of the spindle assembly attached to thegearbox with the sliding sleeve and inner drive rod in a first position.

FIG. 5 is the cross section of the spindle assembly of FIG. 4 with thesliding sleeve and inner drive rod in a second, limiting position withthe sleeve contacting a dowel rod.

FIG. 6 is a cross sectional end view of the spindle assembly showing across-section taken through line 6-6 of FIG. 5.

FIG. 7 is a perspective view of the spindle assembly with a portion ofthe outer member of the spindle and retainer socket screws removed sothat internal components of the spindle are visible. The sleeve is shownin the first position of FIG. 4.

FIG. 8 is a diagrammatic representation of a horizontal directionaldrilling machine attached to a drill string.

DETAILED DESCRIPTION

In many horizontal directional drilling applications it is preferable toutilize a dual pipe system. Dual pipe systems are particularly usefulfor drilling through rock, as the rotation of the inner pipe and outerpipe may be used, independently of one another, to drive rotation of adrill bit and to change the orientation of a steering feature. Anexample of a dual pipe system is disclosed in U.S. Pat. No. 9,765,574,issued to Slaughter, Jr. et al (“Slaughter”), the contents of which areincorporated herein by reference.

With reference to FIG. 8, a directional drilling machine 10 comprises acarriage 12. The carriage 12 provides axial and rotational force and isconfigured to connect sections of drill pipe 14 end to end to form adrill string 16. The drill string 16 comprises an outer and innercomponent. The inner pipe string is housed within the outer pipe stringand may rotate independently of the outer pipe string.

The carriage 12 comprises a rotational drive system 20 and a lineardrive system. The linear drive system moves the carriage along a rail toprovide thrust and pull-back during a drilling operation. The rotationaldrive system 20, such as the system shown in FIG. 1, is configured toprovide torque for adding and removing pipe sections 14 from the drillstring 16, and to provide the axial and rotational force used indrilling and backreaming procedures.

With reference to FIGS. 1 and 2, the rotational drive system 20, orgearbox, comprises an inner pipe motor 22 and an outer pipe motor 24.The outer pipe motor 24 provides torque to the outer pipe string and theinner pipe motor 22 provides torque to the inner pipe string. Torque istransferred from the gearbox 20 to the drill string 16 through a spindle30. The spindle 30 has inner and outer components, as shown in FIGS.2-7, which are preferably substantially centered about a longitudinalaxis 31. The axis 31 is also an axis of rotation for the inner and outercomponents of the spindle 30.

The gearbox 20 comprises an outer output gear 26 and an inner outputgear 28. The outer output gear 26, driven by the outer motor 24,transmits torque to an outer drive shaft 32. Likewise, the inner outputgear 28, driven by the inner motor 22, transmits torque to the innerdrive shaft 34. The inner drive shaft 34 and outer drive shaft 32 rotateindependently of each other. The outer drive shaft 32 is supported by aplurality of outer drive shaft bearings 36. Likewise, the inner driveshaft 34 is held in place by a plurality of inner drive shaft bearings37. The inner 34 and outer 32 drive shafts transmit torque to the drillstring 16 through the spindle 30.

With reference to FIGS. 3-7, components of the spindle 30 are shown. Thespindle 30 comprises an outer member 40 which is rotationally joined tothe outer drive shaft 32 by a plurality of retainer socket screws 42disposed in a flange 44 of the outer member 40. The inner drive shaft34, or a stub joined thereto, is disposed within a cavity 46 formed inthe outer member 40. The outer member 40 has an end 48 which isconfigured for connection to an outer member of the drill string 16. Theouter member 40 may also have an opening for a connection to a wireline.

An inner drive rod apparatus 50 is disposed within the outer member 40.The inner drive rod apparatus 50 comprises a collar 52, a drive rod 54,and a hollow sleeve 56. The collar 52 is configured for connection to aninner member of a dual member drill string 16. As shown, the collar 52has a torque-transmitting inner profile for imparting rotation to theinner member of the drill string 16. The hollow sleeve 56 may be formedintegrally with the drive rod 54 or may be joined by a circumferentialweld 58.

The hollow sleeve 56, as shown, has an internal profile 60 whichconforms to an outer profile 62 of the drive shaft 34. The profiles 60,62, are configured for torque-transmitting connection during rotation ofthe drive shaft 34. However, the profiles 60, 62 are also configured toallow sliding relative movement between the drive shaft 34 and hollowsleeve 56 within a range of motion.

As best shown in FIG. 6, the profiles 60, 62 comprise complementaryinterlocking splines. However, other geometry may be utilized,including, but not limited to polygonal profiles, protrusions ordepressions with torque-transmitting elements, and the like. Further,while the profile 60 of the sleeve 56 is shown on its inner surface andthe profile 62 of the drive shaft 34 on its outer surface, otherorientations which allow relative axial movement but allow torquetransmission may be utilized.

A spring 70 is disposed between the drive shaft 34 and the drive rod 54.The spring 70 biases the drive rod 54 to a forward position as shown inFIG. 4, away from the gearbox 20. As drilling operations continue, thedrive rod 54 may be forced in a direction toward the gearbox 20. Asshown in FIG. 5, as the spring 70 compresses, the inner drive rod 54 andsleeve 56 are forced axially towards the gearbox 20.

With reference again to FIG. 8, during makeup of a pipe section 14 tothe drill string 16, inner and outer pipe connections are made upsimultaneously. There is, however, the potential for misalignmentbetween the ends of the inner pipe sections while adjacent outer pipesections are threadedly connected. This scenario can cause the innerpipe section which is attached to the inner drive rod 54 to beunintentionally forced axially toward the gearbox 20. If the inner driverod 54 is forced into the gearbox 20, the axial force may be transferredto one or more of the plurality of inner drive shaft 34 or gearboxbearings 37. The force exerted on the bearings 37 may cause considerabledamage to the gearbox 20.

The present invention solves this problem by transferring the axial loadof the inner drive rod 54 to the outer member 40, and therefore to theouter drive shaft 32. The outer gearbox bearings 36 are much larger thanthe inner gearbox bearings 37 and may withstand the axial loads whichmay be exerted by the inner drive rod.

The spindle 30 comprises a stop member 80 defining a limit of the axialmovement of the sleeve 56 in a direction toward the gearbox 20. The stopmember 80 is preferably transverse to the longitudinal axis 31 of thespindle 30. The sleeve 56 terminates in a shoulder 57. This shoulder 57,at its limit of axial movement, contacts the stop member 80.

The stop member 80 is disposed through the outer member 40. As a result,axial force transmitted through the drill rod 54 and sleeve 56 willtransfer to the outer member 40 (and thus components of the outermember's rotational drive) rather than the inner drive shaft 34. Thestop member 80 is positioned, as best shown in FIG. 6, such that itreduces the effective inner diameter of the cavity 46 such that it isless than an outer diameter of the sleeve 56, but greater than the outerdiameter of the drive shaft 34.

As shown, the stop member 80 comprises two spaced-apart dowel pins 82.Each dowel pin 82 is trapped within a pair of transfer bolts 84.Through-holes 86 are provided in the flange 44 of the outer member 40.The through-holes 86 are spaced such that the pins 82 sit parallel toeach other, with one pin situated on each side of the inner drive shaft34. The distance between the parallel pins 82 is greater than thediameter of the inner drive shaft 34, but less than the diameter of thesleeve 56. This allows the inner drive shaft 34 to rotate independentlyof the outer member 40 without interference from the dowel pins 82, butdoes allow engagement between the shoulder of the sleeve 56 and thedowel pins 82. The transfer bolts 84 are preferably sealing bolts toprevent leakage of drilling fluid.

Upon engagement of the sleeve 56 with the dowel pins 82, the axial forcethat would have been transmitted to the inner drive shaft 34 is nowtransmitted to the outer member 40, and subsequently to the outer driveshaft 32. As stated above, the outer drive shaft 32 is designed toregularly withstand high axial loads.

To assemble the spindle 30, the outer member 40 is placed over theassembled inner drive components, including the drive rod 54, sleeve 56and inner drive shaft 34. The outer member 40 is then attached to thegearbox 20 with the retainer socket screws 42. Finally, the dowel pins82 are inserted into the through holes 86 in the flange 44 and held inplace by the installation of the transfer bolts 84.

As shown, the spindle 30 is configured to run drill pipe 14 in the“pin-up” configuration. Each outer pipe section comprises a pin end anda box end. The outer member 40 comprises a box end 90 that maythreadedly engage with the pin end of an outer pipe section. The innerdrive rod 54 is attached to the collar 52, which may likewise provide ahexagonal box end 92 for connection to an inner pipe section. Othergeometric shapes, such as is provided for in Slaughter, may also beused.

Each inner pipe section comprises a pin end with a complementaryoutwardly facing geometric shape that is slideably receivable within thecollar 52. Each inner pipe section comprises a box end and a pin end.This configuration provides transmission of torque between the innerdrive rod and an adjacent inner pipe section and between adjacent innerpipe sections. The inner drive shaft 34 and drive rod 52 may comprise aninternally-disposed fluid passage 95 centered upon the longitudinal axis31 of the spindle 30. The passage 95 may be used for the transmission ofdrilling fluid downhole.

The various features and alternative details of construction of theapparatuses described herein for the practice of the present technologywill readily occur to the skilled artisan in view of the foregoingdiscussion, and it is to be understood that even though numerouscharacteristics and advantages of various embodiments of the presenttechnology have been set forth in the foregoing description, togetherwith details of the structure and function of various embodiments of thetechnology, this detailed description is illustrative only, and changesmay be made in detail, especially in matters of structure andarrangements of parts within the principles of the present technology tothe full extent indicated by the broad general meaning of the terms inwhich the appended claims are expressed.

What is claimed is:
 1. An apparatus, comprising: an inner memberdisposed along a longitudinal axis; an outer member at least partiallysurrounding the inner member and disposed about the longitudinal axis;an inner drive shaft coupled to a motor; a hollow sleeve joined to theinner member and in sliding, torque-transmitting engagement with theinner drive shaft; and at least one pin disposed through the outermember and transverse to the longitudinal axis, configured to transmitaxial force from the hollow sleeve to the outer member.
 2. The apparatusof claim 1 wherein the at least one pin comprises two pins.
 3. Theapparatus of claim 1 wherein: the hollow sleeve has an inner surfacedefined by splines; and the inner drive shaft has an outer surfacedefined by splines, complementary to the splines of the hollow sleeve.4. The apparatus of claim 1 further comprising a compression springdisposed between the inner member and the inner drive shaft.
 5. Aspindle, comprising: an inner drive rod apparatus disposed about alongitudinal axis, comprising: a drive shaft; an inner drive rod,configured for connection to an inner member of a dual-member drillstring; and a hollow sleeve, having a first end, a second end, and aninternal surface, wherein the hollow sleeve is slidingly supported androtationally coupled to the drive shaft at the internal surface of thesleeve and joined to the drive rod at the first end of the sleeve; ahollow outer member at least partially disposed about the inner driverod apparatus, the outer member being independently rotatable relativeto the inner drive rod apparatus; and at least one stop member supportedby the outer member, configured to engage with the second end of thehollow sleeve.
 6. The spindle of claim 5 in which the at least one stopmember comprises two dowel pins disposed through the outer hollowmember.
 7. The spindle of claim 6 in which the two dowel pins aredisposed on opposed sides of the drive shaft at a distance greater thanan outer diameter of the drive shaft but less than an outer diameter ofthe hollow sleeve.
 8. The spindle of claim 5 further comprising acompression spring disposed between the inner drive rod and the driveshaft.
 9. The spindle of claim 5 in which the hollow sleeve is joined tothe inner drive rod by a weld.
 10. The spindle of claim 5 furthercomprising a collar, in which the collar is attached to the inner driverod and configured for connection to a pin end of an inner member of thedrill string.
 11. The spindle of claim 5 in which the at least one stopmember is transverse to the longitudinal axis of the inner spindleassembly.
 12. A drilling machine, comprising: a gearbox comprising: afirst motor; a first output gear rotationally driven by the first motor;a second motor; and a second output gear rotationally driven by thesecond motor; and the spindle of claim 5; wherein the hollow outermember is rotationally driven by the first output gear; and wherein thedrive shaft of the inner drive rod apparatus is rotationally driven bythe second output gear.
 13. The drilling machine of claim 12 wherein:the hollow sleeve defines a limit position, wherein the hollow sleevecontacts the stop member in the limit position; and wherein the stopmember is configured to transfer axial force from the hollow sleeve tothe outer member when the hollow sleeve is in the limit position. 14.The spindle of claim 5 in which: the drive shaft of the inner spindlecomprises an outer surface defined by a plurality of torque-transmittingfeatures; and the inner surface of the hollow sleeve is defined by aplurality of features complementary to the torque-transmitting featuresof the drive shaft.
 15. The spindle of claim 14 in which thetorque-transmitting features are splines.
 16. An assembly for connectinga dual-member drill string to a gearbox, the dual-member drill stringcomprising independently rotatable inner and outer members, the assemblycomprising: an inner assembly, connected at a first end to the gearboxand a second end to the rotatable inner member of the dual-member drillstring, the inner assembly comprising: a drive shaft, rotatable about alongitudinal axis and having a first outer diameter; a drive rodconfigured for torque-transmitting connection to the rotatable innermember; and a hollow sleeve having a second outer diameter, the sleevebeing joined to the drive rod and partially surrounding the drive shaftin a torque-transmitting relationship; wherein the hollow sleeve isconfigured to move axially relative to the drive shaft; an outerassembly comprising a cavity in which the drive shaft and hollow sleeveare partially housed, the cavity defining a first inner diameter, inwhich the first inner diameter is greater than the first outer diameterand the second outer diameter; and a stop member disposed through theouter assembly and extending into the cavity, wherein an effective innerdiameter of the cavity at the stop member is greater than the firstouter diameter and less than the second outer diameter.
 17. The assemblyof claim 16 further comprising a dual member drill string having anindependently rotatable inner member and outer member, in which: theouter assembly is joined to the outer member; and the drive rod isconnected to the inner member.
 18. The assembly of claim 17 in which thedrive rod comprises a collar having a torque-transmitting profile, andwherein the inner member is partially disposed within the collar. 19.The assembly of claim 16 in which the stop member comprises two pinsdisposed within the cavity and transverse to the longitudinal axis.